Re: [load balancing] F5 LTM marking nodes down

From: LeMay, John <JLeMay [izzat] KHOV.COM>
Date: Wed Nov 07 2007 - 11:42:04 EST

I agree, however increasing those timeouts may hide the issue or as I
stated possibly indicate a timing issue. The trace is ideal, but
depending on how much traffic is going through the device that may be
like looking for a needle in a haystack.

--
John LeMay
K. Hovnanian Companies, LLC
Systems Engineer
Ph. 732 383-2195
jlemay@khov.com
-----Original Message-----
From: lb-l-bounces@vegan.net [mailto:lb-l-bounces@vegan.net] On Behalf
Of Omachonu Ogali
Sent: Wednesday, November 07, 2007 11:22
To: Load Balancing Mailing List
Subject: Re: [load balancing] F5 LTM marking nodes down
But if the issue was the frequency of the monitor, he would be seeing
intermittent up/down events from both units, not just the standby. A
network sniff is really needed to see exactly what is going on.
oo
On Nov 7, 2007 10:48 AM, LeMay, John <JLeMay@khov.com> wrote:
>
>
>
> A possible resolution, really a workaround, may be to use custom 
> monitors for http and icmp with increased timer and interval values. 
> I've done this in the past for different reasons, and it doesn't tell 
> you where the issue is of course. If you do go this route, F5 has 
> recommended to me in the past that the timeout should always equal 
> three times the interval plus one second (the online help recommends 
> the same). This may even give a clue to the root cause of the issue. 
> If you increase the timeout and interval and the issue goes away,
chances are the issue is latency of some sort.
>
> If you can get this to happen at predictable times, you could always 
> run tcpdump on the standby box during that time period and see if 
> there are any clues in the trace.
>
> --
> John LeMay
> K. Hovnanian Companies, LLC
> Systems Engineer
> Ph. 732 383-2195
> jlemay@khov.com
>
>
>
>  ________________________________
>
> From: lb-l-bounces@vegan.net [mailto:lb-l-bounces@vegan.net] On Behalf
> Of Julian Grunnell
> Sent: Wednesday, November 07, 2007 10:14
> To: lb-l@vegan.net
> Subject: [load balancing] F5 LTM marking nodes down
>
>
>
>
> Hi - got a query regarding alerts that a STANDBY LTM 1500 is 
> generating, we have a pair of LTM 1500's in an ACTIVE / STANDBY setup
using vlangroups.
> Version 9.3.0 is installed. The nodes behind the LTMs are Microsoft 
> 2003 IIS 6.0 servers using ACTIVE / PASSIVE NIC teaming.
>
> We see on a daily basis the STANDBY LTM marking nodes as DOWN and then
> UP for both icmp and HTTP health checks, often a minute or two 
> inbetween the state changes, the ACTIVE LTM NEVER logs anything.
>
> At the times the alerts are seen the guys that admin the web servers 
> cannot see anything wrong at all - the servers are up and running. And
> the guys that admin the network infrastructure cannot see any errors 
> at all from any of the switchports. What I have seen is that when the 
> STANDBY LTM has the node marked DOWN I can both ping the node in 
> question and make a port 80 connection from the STANDY LTM which is
just bizarre.
>
> If anyone has any ideas on where the problem might lie, things that 
> would be worth checking or even better have had this problem before 
> and how to resolve it I would appreciate it!!
>
> Thanks - Julian.
>
>
> Julian Grunnell
> 3rd Line Technical Support
> Pipex Communications
>
> Tel: 01296 300227
> Mob: 07803 649593
> Web: http://www.pipex.com/
>
> This e-mail is subject to: http://www.pipex.net/disclaimer.html
>
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Received on Wed Nov 7 11:54:29 2007

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